Perforating apparatus



y 16, 1963 R. WARMT 3,098,143

PERFORATING APPARATUS Filed Feb. 24, 1961 2 Sheets-Sheet 1 INVENrO/P;

y 63 R. WARMT 3,098,143

PERFORATING APPARATUS Filed Feb. 24, 1961 2 Sheets-Sheet 2 mmswrolez W MM 1 A United States Patent Eds The present invention relates to a method and apparatus for finely perforating webs or tapes, such as webs of cigarette paper.

In order to control the quantities of fresh air and of cooling air through the wrapper of the cigarette when the cigarette is being smoked, cigarette paper is used which has evenly distributed fine perforations. The perforations may be distributed throughout the entire area of the wrapper or they may be provided only in certain predetermined area portions thereof.

Particulariy in the case of very thin foil-like material such as cigarette paper, it is not possible to obtain perforations of the sought for small dimensions by means of a stamping process. It has, therefore, been proposed, for example in German Patent No. 750,662, to perforate the paper electrically by producing arc-overs between pairs of electrodes. This is accomplished by fashioning a roller over which the paper web passes as one electrode and by providing a plurality of pointed electrodes of the opposite polarity in such a manner that the paper passing between the roller and the pointed electrodes will be pierced and thus perforated by arc-overs. Experience has shown, however, that the distribution of perforations obtained in such a manner is not predeterminable. This is so because the arc-overs will occur at the thinnest portions of the paper web, i.e., those portions of the web which have the least dielectric strength. Consequently, the distribution of the perforations is completely uncontrollable and irregular.

It is, therefore, an object of the present invention to provide a method and apparatus for continuously perforating thin sheet-like webs, which method and apparatus overcome the above disadvantages.

It is another object of the present invention to provide an electrical method and apparatus for providing sheetlike material with perforations, which method and appanatus operate very eificiently.

It is yet another and very important object of the instant invention to provide a way in which the perforations are applied uniformly.

The objects of the present invention also include the provision of a perforating method and apparatus in which the size of the perforations can be controlled.

Still another object of the present invention is the provision of a perforating method and apparatus which can treat even very thin sheet-like material, such as cigarette paper.

With the above objects in view, the present invention resides mainly in applying a high frequency field between two electrodes and by producing an arc-over by means of a high voltage pulse applied to these electrodes. Thus, the space between the electrodes, i.e., the space through which the sheet-like web is fed, is prc-ionized by a high frequency field, the voitage of the source of high frequency being such that the field is of insufficient strength to cause arc-over between the electrodes and through the particular material of the web being fed therebetween. This arc-over is produced by a high voltage device which is controlled by an impulse generator, so that breakdown of the field, and consequently the arc-over between the electrodes and through the web, is controlled by the impulse generator. This is done whenever the electrode tips are in discharge position nearest to the web.

The present invention is particularly applicabie to the perforation of cigarette paper, it being understood, however, that the expression sheet-like web, as used throughout the instant specification and claims, is not specifically limited to cigarette paper but includes other sheet-like or foil-like material in strip form.

Additional objects and advantages of the present invention will become apparent upon consideration of the following description when taken in conjunction with the accompanying drawings in which:

FIGURE 1 is a schematic perspective view of an apparatus according to the present invention.

FIGURE 2 is a front view of an electrode disc forming part of the apparatus.

FIGURE 3 is an elevational view, partly in section, showing the electrode disc and the manner in which it is mounted for rotation.

Referring now to the drawings, FIGURE 1 shows a base ll carrying a support in the form of an angle iron 2. An upwardly extending plate 4 is arranged between and welded or otherwise firmly secured to the support 2 and to another support constituted by a channel piece 3 of U-shaped cross section. The apparatus turther includes a rearwardly extending platform 5 carrying a mounting block 6 which rotatably supports the shaft of an electric motor 7, the latter including a gear box 8. The motor 7 is energized by way of an electric line 9 having a connector plug it? which is adapted to be plugged into an appropri ate outlet of a source of electric energy (not shown). The end of the shaft of motor 7 which protrudes beyond the block 5 carries a pulley 11, there being a belt 12 which runs over this pulley and a second, smaller pui-ley 13 which is mounted on a shaft 15, the latter being rotatabiy mounted in a mounting [block 14. The forward end of the shaft 15, as viewed in FIGURE 1, carries an electrode roller 16.

The apparatus further comprises a support 17 which is fixedly connected to the support 2 and which mounts a carrier 19, the latter being displaceable by any suitable means, as, for example, a threaded spindle 18, and carrying a guide ring 2%. The plate 4- also carries an arm 21 which supports a guide roller 22.. The upper end of the plate d carries a drum 24 mounted on an an axle 2-3, the drum 24 serving as a mount for a supply reel 25 of the sheet-like web to be perforated, such as a supply reel of cigarette paper. The web 36 unwinds from the reel 25 and passes, via the guide roller 22 and the guide ring 21!, over the electrode roller '16 to a further guide roller 26 which is mounted on a shaft 27, the latter being rotatably mounted on a bracket '23.

The base 1 also carries an angle-shaped support 29 which, in turn, carries a shaft 30' mounting a pivotable arm 31 one free end of which rotatably supports a pressure roller 32. The opposite end of the arm 31 carries an extension 33 which is connected by a spring 34 to an angle-shaped outrigger 35, the latter being attached to the base il in any suitable manner (not shown in FIG- URE l). The two rollers 26 and 32; cooperate to keep the paper web 36 under pressure and tension. Unwanted unwinding of the web from the supply reel 25 is prevented by a retaining device comprising an arm 37 carrying a yieldable band 38 which engages the outermost turn of the web wound on the reel, the arm 37 being carried by an extension 39 which is secured to the plate 4-.

The apparatus further comprises a support 40* carrying a driving motor 41 which may likewise be connected to a source of electric energy via an electric line 42 and a connector plug 43. The motor 41 is connected, by means of a belt 44, to a drive pulley 45 of an electrode disc indicated generally at 46, the details of the latter being shown more particularly in FIGURES 2 and 3.

The electrode roller 16 is connected to an electric cable 47, and the electrode disc i6 is connected to an electric cable 48. The cable 457 is connected to a terminal 49 of a high frequency generator 50, and the cable 48 is connected to a terminal 51 of a high voltage device 52. The high voltage device 52 is connected to the high frequency generator 50 by means of an electric cable 53 which is attached to the terminals 54, 55, as shown in FIGURE 1. The high voltage device 52 per se and the high frequency generator '50 per se are known, so that a detailed description of these electrical components is unnecessary.

The high voltage device 52 produces a high voltage of the order of about 15,000 volts at a frequency of about 10 kilocycles, whereas the frequency generated by the high frequency generator is of the order of about megacycles, the voltage of the high frequency generator being negligible. The high voltage device 52 and the high frequency generator 56 are connectible to suitable sources of electricity via electric lines 56, 57, and connector plugs '58, 59.

FIGURES 2 and 3 show the electrode disc 45 in detail. FIGURE 3 shows a mounting bracket s1 having a bearing 62 which rotatably mounts a shaft 63 one end of which carries the above-mentioned drive pulley and the other end of which carries the electrode disc 46, the latter comprising :an insulating disc 64 and a metallic contact disc 65. A plurality of individual electrode rods 65 are pressed against the contact disc 65 by means of retaining dowels 67, the latter being formed with bores through which the electrode rods 66 extend and with external threads which carry nuts 63, washers 69 being provided between the nuts and the insulating disc 64, as shown. The contact disc 65 is in electrical contact with the slip ring '70 which is electrically insulated from the shaft es. The slip ring '70 is electrically connected to the cable 48.

FIGURE 2 shows the electrode disc 46 as carrying sixteen electrode rods es, it being evident that an appropriate greater or lesser number of rods may be provided, as desired. Each rod 66 passes through a bore in the ring 64, lined by a ceramic sleeve '71, and the radial position of the outermost end of each rod can be adjusted as required, i.e., the distance which each electrode rod extends outwardly from the electrode disc can be set.

The operation of the apparatus is as follows:

The paper web 36 unwinds from the supply reel 25 and runs over the guide roller 22 and through the guide ring 20, in which the web is arched somewhat in a transverse di-rection. The web then moves over the electrode roller 16 and thus between this roller It? and the electrode disc 46. From there, the web travels between the guide roller 26 and the pressure roller 32 and thence to the next stage where the perforated paper web is used, as, for example, a cigarette making machine.

As explained above, the electrode disc 46 is connected via cable 43 to the high voltage device 52. The latter incorporates an impulse generator, of conventional design and therefore not shown in the drawing, which impulse generator controls the output of the device 52;. The high frequency generator 59 produces the ionization field in the air gap between the electrode disc and the electrode roller 16. Consequently, spaced voltage impulses will be applied across the electrode rods 66 and the electrode roller 16, and these spaced voltage pulses will produce arc-overs which result in perforations in the web 36 that correspond to the sequence of the lines of electrodes.

As stated above, the illustrated electrode disc 45 carries sixteen electrode rods 66 which are evenly distributed throughout the circumference of the disc, each rod having a diameter of about 0.5 millimeters and being adjustably held in the ceramic sleeve '71 which lines the corresponding bore of the insulating disc 64. The length of the arc segment between the outer ends of adjacent electrode rods 66 corresponds to the width of the paper Web 36. If the electrode disc 46 is rotated at, for example, a speed of 1,500 revolutions per minute, then 1,500 l6=24,000 electrodes are passed over the web every minute, i.'e., 24,000 lines of perforations will be produced every minute. The number of perforations produced per minute can then be calculated by multiplying the frequency of the impulse generator of the high voltage device, namely, 10 kilocycles, by the time interval of seconds, or 600,000 perforations per minute. Thus, a line of perforations on the web 36 will consist of :25 perforations per line The distance between the lines will be determined by the rate at which the web as is advanced.

It will be seen from the above that the constant high frequency field which produces the pie-ionization of the air in the gap between the electrode disc 46 and the electrode roller 16, and the impulses which are superposed upon this high frequency field, coact to generate arcovers which will follow a predeterminable path through the air and thus through the paper web to be perforated.

By connecting a plurality of apparatus of the type described above in series with each other, i.e., by feeding a web successively through a plurality of perforating apparatus, the density of the perforations can be changed.

Also, by appropriate feeding of the web, it is possible to obtain perforations which run in different directions. That is to say, the lines of perforations need not run exactly at right angles to the direction of travel of the web 36 if the axis about which the electrode disc 46 rotates is not parallel to the feed direction of the web, so that by inclining the axis of the disc 46 relative to the web, the lines of perforations may be made to run at a predetermined an le relative to the web.

it is also possible to modify the electrode disc in such a manner that the number of the electrode rods 66 as well as their angular spacing about the periphery of the disc are adjustable. In this way, the apparatus may be adapted for use with webs of different widths. Also, there may be a plurality of electrode rows, and the distance between the rows may be made adjustable.

It will be appreciated that the amplitude of the voltage produced by the high voltage device 52 can be adjusted so as to adapt the apparatus to the dielectric strength of the particular material which is to be perforated and to the size of the perforations desired.

It will be understood that the above description of the present invention is susceptible to various modifications, changes and adaptations, and the same are intended to be comprehended within the meaning and range of equivalents of the appended claims.

-I claim:

1. in a perforating apparatus, the combination which comprises: means for moving a sheet-like web along a predetermined feed path; an electrode roller carrying a plurality of electrodes arranged in at least one row and evenly distributed about the periphery of said electrode roller, said electrode roller being arranged on one side of a web fed along said feed path; counter electrode means rranged on the opposite side of a web fed along said feed path and having a potential different from that of said electrode roller; a high frequency generator connected to said electrode roller and to said electrode means for producing a constant high frequency field in the region where said electrode roller is closest to a web fed along said feed path, said field being of a strength insufiicient to cause arc-over between said electrode roller and said electrode means and through the web being fed along said feed path; and a high voltage source having an impulse generator connected to said electrode roller and to said electrode means for producing high voltage impulses in dependence of the approaching of said electrodes to the web, where by arc-overs occur between said electrode roller and said electrode means which produce uniformly distributed perforations of the web.

2. The combination defined in claim 1 wherein said electrode roller includes an insulating ring having bores through which said electrodes extend such that the tips of said electrodes are located at the periphery of said ring.

3. The combination defined in claim 1 wherein said counter electrode means comprise a second electrode roller which is mounted for rotation about an axis which is at right angles to the direction of said feed path.

4. The combination defined in claim 1 wherein said electrode roller is mounted for rotation about an axis which is parallel with respect to the direction of said feed path.

5. The combination defined in claim 1 wherein the positions of said electrodes about the periphery of said roller are adjustable.

6. The combination defined in claim 1 wherein said high voltage source is adjustable, whereby the output voltage can be adjusted to correspond to the dielectric strength of the web and to the size of the perforations desired.

7. In a perforating apparatus, the combination which comprises: two electrode means at least one of which is a roller having a plurality of electrode elements distributed about its periphery; means for feeding between said electrode means a sheet-like web to be perforated; means for producing a preionizing high frequency field between said electrode means, said field being of a strength insufiicient to cause arc-over between said electrode means and through the web being fed therebetween; and means for periodically applying high voltage impulses to said electrode means sufficient to cause arc-over between said electrode means, whereby the web will be perforated uniformly.

References Cited in the file of this patent UNITED STATES PATENTS 1,250,140 Chapman Dec. 18, 1917 2,545,208 Meaker Mar. 13, 1951 2,868,947 Williams Jan. 13, 1959 2,876,386 Fefer et a1 Mar. 3, 1959 2,939,065 Matulaitis May 31, 1960 FOREIGN PATENTS 593,891 Great Britain Oct. 28,. 1947 

7. IN A PERFORATING APPARATUS, THE COMBINATION WHICH COMPRISES: TWO ELECTRODE MEANS AT LEAST ONE OF WHICH IS A ROLLER HAVING A PLURALTIY OF ELECTRODE LEMENTS DISTRIBUTED ABOUT ITS PERIPHERY; MEANS FOR FEEDING BETWEEN SAID ELETRODE MEANS A SHEET-LIKE WEB TO BE PERFORATED; MEANS FOR PRODUCING A PREIONIZING HIGH FREQUENCY FIELD BETWEEN SAID ELECTRODE MEANS, SAID FIELD BEING OF STRENGTH INSUFFICIENT TO CAUSE ARC-OVER BETWEEN SAID ELECTRODE MEANS AND THROUGH THE WEB BEING FED THEREBETWEEN; AND MEANS FOR PERIODICALLY APPLYING HIGH VOLTAGE IMPULSES TO SAID ELECTRODE MEANS SUFFICIENT TO CAUSE ARC-OVER BETWEEN SAID ELECTRODE MEANS, WHEREBY THE WEB WILL BE PERFORATED UNIFORMLY. 